A central problem in the area of assessment in the classroom has been in the way we often confuse marking and feedback. As Dylan Wiliam points out in our discussion, there is an extraordinary amount of energy expended by teachers on marking and often very little to show for it in the way of student benefit. Although feedback is one of the most effective drivers of learning, one of the more surprising findings is that a lot of it actually has a negative effect on student achievement.

A set of marked books is traditionally seen as an effective proxy for good teaching but there is a lot of evidence to say that this might not always be the case. This problem is on…